Why after linking the OpenCV libraries, Mat objects are still 'undefined'?

[georgiav]

I tried that and it still doesn't work apparently

[SGaist]

Please provide the information directly.
What exactly did you try ?
What is the error your get ?

[georgiav]

I changed the include statements to that and in the .pro file the INCLUDEPATH is /usr/local/include/opencv4

[SGaist]

@SGaist said in Why after linking the OpenCV libraries, Mat objects are still 'undefined'?:

Did you notice the "opencv4" folder that is missing from your INCLUDEPATH statement ?

Either add it there or to your include statements.

I wrote "either" which means one or the other, not both.

[georgiav]

So I changed it in the main.cpp file because otherwise I got those errors . Now in the .pro file is /usr/local/include.
I still get the same errors

The last error I don't understand because I wrote opencv2/core/core.hpp not opencv2/core.hpp and I cleaned the project again before

[jsulm]

@georgiav Change INCLUDEPATH in your pro file so, that it points to /usr/local/include/opencv4 and change your includes like

#include "opencv2/...

[georgiav]

@jsulm Hi, I tried that before and I got those errors of 'file not found' ( photo above)

[SGaist]

Here is a minimal example adjusted to the paths you shown to us:

.pro file:

TEMPLATE = app
TARGET = test_opencv
INCLUDEPATH += .
INCLUDEPATH += /usr/local/include/opencv4
 
LIBS += -L/usr/local/lib/ -lopencv_core
SOURCES += main.cpp

main.cpp:

 #include <opencv2/core.hpp>
  
 int main(int argc, char **argv)
 {
      cv::Mat mat;
      return 0;
 }

[georgiav]

@SGaist Yes, this seems to work fine! Thank you very much!

[Pablo J. Rogina]

@georgiav said in Why after linking the OpenCV libraries, Mat objects are still 'undefined'?:

this seems to work fine!

so please don't forget to mark your post as solved!